At Wed, 22 Oct 2008 09:55:01 +1300, Eliot Blennerhassett wrote:
On Tuesday 21 October 2008 19:34:49 Takashi Iwai wrote:
Sorry, I don't understand well your question. Do you want to see the alsa-plugin chain of a running application from the outside,
Yes. Basically see something that looks like the result of "aplay -v", but for a running app from the outside.
E.g. to see if the app is using dmix, plughw etc, what parameters the app sees vs how the card is accessed.
Best if this info was available like the proc files for the driver, but if it required running the app in a special context (debugger-like or LD_PRELOAD) that would probably still be useful.
The app should not have to be recompiled.
Well, right now it's almost impossible because the alsa-lib stuff is purely a user-space thing and not exposed to anywhere else.
An easy hack is to add snd_pcm_dump() to snd_pcm_hw_params() in alsa-lib (better with a conditional check, such as a certain environment variable). But this function may be called recursively, it should have a certain re-entrace check.
Takashi